1. Field of the Invention
The present invention relates to an imaging optical lens assembly, and more particularly, to a compact imaging optical lens assembly used in portable electronic devices.
2. Description of the Prior Art
In recent years, with the popularity of mobile phone cameras, the demand for compact imaging lenses is increasing, and the sensor of a general photographing camera is none other than CCD (charge coupled device) or CMOS device (Complementary Metal Oxide Semiconductor device). Furthermore, as advanced semiconductor manufacturing technology has allowed the pixel size of sensors to be reduced and the resolution of compact imaging lenses has gradually increased, there is an increasing demand for compact imaging lenses featuring better image quality.
A conventional compact imaging optical lens assembly for mobile electronics, such as the one disclosed in U.S. Pat. No. 7,365,920, generally comprises four lens elements, wherein two spherical-surface glass lenses are used as the first and second lens elements, and being adhered together to form a doublet and thereby to correct the chromatic aberration. Such an arrangement of optical elements, however, has the following disadvantages: (1) the freedom of the system is curtailed due to the employment of excess number of spherical-surface glass lenses, thus the total track length of the system cannot be reduced easily; (2) the process of making the glass lenses adhered together is complicated, posing difficulties in manufacture. In addition, a four independent lens elements optical system is disclosed by U.S. Pat. No. 7,643,225, comprising multiple aspheric lens elements, which effectively shortens the total track length and obtains high image quality.
However, due to the popularity of high standard mobile devices such as smart phones and PDAs (Personal Digital Assistant) driving the rapid improvements in high resolution and image quality of the compact imaging lens systems, conventional four lens elements systems no longer satisfy the higher level camera modules. Furthermore, with the current trend for high performance and compact design in electronic products, the need for high resolution and high performance compact imaging optical lens assembly is very crucial in high level electronics development.
Therefore, a need exists in the art for an imaging optical lens assembly that features better image quality, maintains a moderate total track length and is applicable to compact portable electronic products.